Quietly and without ceremony, a next-generation Barcelona side -- average age 21 for the outfield players and including the 21st graduate that coach Pep Guardiola has brought through from the club's youth system -- eased to a 4-0 win over Belarusian side BATE Borisov at the Nou Camp, equalling the Champions League record of 20 goals in the group stage.

It is a story which explains why Barcelona obsess United and City in equal measure and why Alex Ferguson has become especially mesmerised with the elixir of youth as he moves towards his 70th birthday.

His televised discussion with his former goalkeeper Fabien Barthez passed almost without comment amid the euphoria of his 25th anniversary at United last month, but it revealed how the idea of conquering with young players has taken an extraordinary hold of him.

foundation

"My philosophy has always been with young players. I prefer young players," he told Barthez. "The foundation is built upon a collection of players who stay for a long time. It is easy, then, to build a family of people who grow together, understand each other and are friends, because that is what times does -- it builds friendships."

Notice how a defence of youth was also the first thought on Ferguson's mind in the bitter chill of defeat in Basel on Wednesday which consigns United to the Europa League.

"We have enough young players to get us through," he said. There is a certain valour in maintaining the course on which he has set United and a romance, binding him to the club's glorious past.

"The romance started with the Matt Busby team and then he rebuilt that team 10 years later to win the European Cup," Ferguson told Barthez.

But United's catastrophic exit from the tournament has, frankly, revealed that the young players are not ready, however much hope is draped around their slender shoulders.

United have trudged dismally around England and Europe in the past three months and even factoring in Ferguson's ability to confound the doubters, it is difficult to foresee them retaining the Premier League title.

United, who sacrificed domestic ascendancy to Chelsea after their group-stage elimination six years ago, are in flux. It may take them some time to emerge, given Ferguson's little-reported admission last autumn, at the height of the saga in which Wayne Rooney questioned United's ability to sign "world-class players".

"When you see Manchester United at the moment with all these young players, 14 under 22, you can see Manchester United three years ahead," Ferguson said on October 21, 2010 -- the night of Rooney's searing statement, questioning the club's ambition.

The problem is that no club can afford to wait three years. Barcelona have struck gold in recognising that the youth-team coach is the second most important professional at their club and anointing that individual -- Guardiola -- as first-team coach.

But critical to the gulf they have opened up over United, the Spanish side have been known to splash out. Their net spend over the past six years has been £200.3m -- with David Villa, Gerard Pique and Cesc Fabregas all added to the ranks when required.

United's net spend in the same period has been £55.14m, a figure skewed by the £80m sale of Cristiano Ronaldo in 2009, certainly, but one which is actually lower than both Sunderland and Stoke City, whose net outgoings on players in the same period have been £62m and £61.19m respectively.

That the purchases of Phil Jones, Chris Smalling and Javier Hernandez have contributed to that total reveals this is a complicated picture, though United's desperate desire to hold onto Rooney shows how the spirit of the side has become unhealthily channelled into one player.

A year on from his insurrection, Rooney finds himself chief cook and bottlewasher because the club who had pretensions to challenge Barca lack anyone else to do a job in midfield. Benfica's Nicolas Gaitan looks like the minimum requirement, to lift some of the ridiculous expectations heaped on Tom Cleverley.

"I'm just getting a little bit worried that it seems our whole future depends on Tom Cleverley," United legend Lou Macari said recently. "It's getting a little bit out of hand." The burden was never like this for Ronaldo and Rooney.

The surprising part of the equation has been Ferguson's reticence to blood some of that youth in which he holds such store. Ravel Morrison revealed in his first 15 minutes of a second-half display against Crystal Palace last week why United's coaches are so determined to persevere with such a troubled soul, yet he has not started a match for the club.

Paul Pogba -- rather challenged that night -- offers more of the promise which United's relegation to the Europa League may just present a chance to flourish.

The mood across at City was far less dark, yesterday. Roberto Mancini reiterated that he feels his club are not in the same bracket as Barca, Real Madrid or even Bayern Munich, though their own net spend has left him believing that his time will come next autumn. This explained the good humour with which he batted away the insults of former Arsenal keeper Jens Lehmann.

But Mancini's board do not think the sky is entirely blue and Barca are, again, the cloud looming over it. The time has arrived, in the landscape of financial fair play, when City must sell if they are to buy and must draw on their own young, too.

Yet there is an acceptance at the highest level of the club that the quality of their U-19s leaves them light years behind the Catalan side. Remember the names of Denis Suarez, Abdul Razak and Karim Rekik, certainly, but precious few others seem to belong to the future.

Perhaps the city of Manchester's hopes of European supremacy rest with Barcelona -- and the belief that all clubs' success is cyclical. Ferguson ruminated after last May's Champions League final defeat on the question of "how long it lasts... whether (Barca) can replace that team at some point" and concluded that "it's always difficult to find players like Xavi, Iniesta and Messi all the time, (so it's) probably not (going to last.)"